Many plastic processes such as injection molding, blow molding, compression molding and reaction injection molding among others produce parts which may have flash (extraneous material) that must be removed after the part is molded. Removing this flash by hand is a difficult and physically demanding task. The repetitive nature of the task can lead to repetitive motion injuries such as carpel tunnel syndrome.
Efforts to automate this task using CNC machine tools have encountered several difficulties. The flash must be trimmed to blend with the surrounding part surfaces; however, it is the nature of many plastic parts that the part size and shape may vary from part to part. Therefore it is not possible to create a CNC program to properly trim the part with the precision often required.
An attempted solution to this problem was the development of a "floating head" which was intended to allow the machining head to float and be guided by a bearing on the tool which rolled on the part guiding the trim operation. This approach has certain limitations. The size of the mechanism prevents its use on many parts and makes it difficult to mount on many CNC machines, especially 5 axis heads intended to machine three dimensional parts. Also, it may be necessary to perform both conventional machining, which requires a rigid head, and de-flashing, which requires a floating head on the same part.